1863
July 22 Company A organized as 1st Company New Hampshire Heavy Artillery and mustered in. Stationed at Fort Constitution
September 17 Company B organized as 2nd Company New Hampshire Heavy Artillery and mustered in. Stationed at Fort McClary, Kittery Point
1864
May 6 Companies A and B ordered to Washington, D.C. Attached to Augur’s Command, Defenses of Washington, 22nd Corps, and assigned to duty in the Defenses of Washington, D.C.

Company A at Forts Slocum, Stevens, Totten, Sumner and Batteries Cameron, Parrott, Kendall and Vermont. Company B at Forts Bunker Hill, Saratoga, Lincoln, Bayard, Gaines and Foote.

July 11-12 Companies A and B repulse Early’s attack on Washington
September 2 – October 17 Companies C – L organized and ordered to Washington, D.C., as soon as organized for duty in the Defenses of the city
November 5 Company “M” formed by assignment of 1st New Hampshire Battery, Volunteer Light Artillery but remained detached as a Light Battery.
November 25 Company A ordered to Portsmouth Harbor
June Regiment mustered out. Recruits consolidated to 2 Companies
1865
February Company B ordered to Portsmouth Harbor, N.H.
September 11 Recruits mustered out